I am not altering float height at all. I checked it once, quite some time ago, to make sure it was correct. I did reset it to 14mm from the standard 15mm.

The bike idles on the pilot system. If the float level is correct and the needle/seat is working correctly and the pilot system is correct - you have an idle. 136/5N is a known working setup on multiple members' bikes. My bike has run perfectly fine using main jets from 128 to 150 and needle settings ranging 5N up to DJ140 and 3N from 140 to 150..

I think you have some other problem Zeno. There is a lot that can "go wrong" when handling the carb during a setup change..

 

Well, not much can go wrong when you're just swapping out notch position. Don't even have to remove carb for that.

I realized I may just need to put in some more gas since my Acerbis may be holding the last of the gas in the wings at this point.

But if it's not that... I don't understand what could explain the issue. I was able to get it to run on 5N, it was just too rich in combination with my #40 pilot.

It runs pretty great on 4th notch, but I was hoping I could drop notch down to 3 so that I could unscrew my fuel/air mix screw some more.

 

Well actually I can imagine many things going wrong with pulling the top cover and playing with the clip position - Diaphragm damage, diaphragm seal incorrect, causing vacuum leaks and aberrant slide behavior, DJ washers not installed on top of clip, Needle not set into the needle jet , Plastic "hat" not installed correctly on top of needle. Spring not seated correctly on "hat" and/or cover, etc..

The dropping of a notch so that the fuel screw can unscrew doesn't make sense. The fuel screw sets the idle AFR - the needle sets the fuel curve for RPM ranges between off idle and WOT(up to about 6.5K)... The pilot system does continue to flow an air/fuel mix all the time - But if set correctly, the flow is not suppose to have any measurable impact on AFR once the needle is "in play".. The procedure for setting the fuel screw is straight-forward and gives you a good AFR for the RPM range it services.. With the #40, you have some leeway, you can choose to set it toward lean or rich from midway between drops if you wish.. but once your into the needle, the pilot jet/fuel screw is done..

Now I wanted my #40 to provide 12.8:1 (or so) at idle. I want my needle/main jet to work together to give 12.8:1. I want my main jet to give a 12.8:1 ( above about 6.5k ) - So I was looking for transitions from pilot to needle to main that maintained 12.8:1 ...

 

But if I had any of those problems, wouldn't it affect 4N, too? Although maybe something just happened on this reassembly that didn't happen before (or it's fuel starved).

Oh yeah, good point about the idle mix screw. I just remember PO had a #45 pilot jet in here before and it felt like it affected entire range and fuel/air screw calibration. Does it affect when the engine is already at higher RPMs and you let off the throttle completely? Or is slide and higher circuits in affect even with throttle closed, and vacuum just keeps them open?

I do feel like my mid range of throttle position is still a bit boggy/rich, so I wanted to try 3N (my float height may be different than yours, too - I just know its in spec after caliper measurement + clear tube measurement trick).

I basically can't get lean running symptoms unless my fuel/air mix screw is all the way in, and the gurgling over-rich decel sound still occurs easily at mid-range, although it is much better than it used to be.

 

Well, my educator training is being taxed here. I sense that your having a problem that's got you vexed but a lot of what your saying doesn't make sense - turning the fuel screw "all the way in" shuts down the pilot system. So no idle is possible, probably weird issues with decel, etc..
About the best solution is to use PM to verify that you are running a known working setup and go from there.. BTW, I thought you had a good setup already... You experimenting?

 

False alarm! It was just fuel starvation or hiccups, or a small amount of bad gas/water in gas tank. Sorry for crapping up your thread

I just filled it up with fresh gas and it runs great at 3N! Will go on a proper ride tomorrow to test it out. Current setup is: airbox lid off, clean twinair filter, #40 pilot, 136 dj main, 2206 dj needle, and 3N starting today (was 4N).

I had never been completely satisfied that bike wasn't too rich in midrange. It always gurgled a bit when I cut the throttle, too. It's been much better ever since I swapped out the PO's #45 pilot with the #40, but it still seems a bit on rich side while mid-throttle. WOT is perfect (I think) and pulls hard at cold and warm.

And believe it or not, I've found other instances of people with Keihen CV carbs that were able to idle fine with mixture screw all the way in... not a smooth idle mind you, but bike wouldn't die right away. I remember reading a couple threads with KLR650's and KLX300s being able to do that.

I suspect that even with the Kouba extended mixture screw all the way in, it's not 100% tight and some fuel still makes it through. Or maybe I'm just too scared to overtighten it so I'm NOT seating it all the way in. And yes, my mixture screw has the spring and o-ring in correctly, and no leaks from manifolds or seals.

 

I think your right about the Kouba screw. All the way in should kill the engine. It must have a non-oem design. This may also mean non-oem metering at other positions as well. Unless you bought the wrong one ..?

I guess I'll say, out loud, what I usually say in private, If a known working solution/setup fails to perform properly, you have to go back in and fix whatever you screwed up while performing the setup. For some, that'll be going back in over and over until you get it right. I'm not being condescending - There's a reason why I know of every single "screw up" one can commit while changing a carb setup..LOL

 

Pilot jet along with its' fuel screw and Pilot Air Jet control idle AFR and deceleration AFR, end of story.

Zeno, your KLX300 exhaust is the unknown issue - it should serve to enhance upper RPM power as it is a larger "pipe" than the KLX250's (Similar in size to my FMF system.) If so, it should also demand less fueling in the midrange - the needle's area of influence - over a standard KLX250 header+slipon. It should demand about the same fueling on top as my FMF testing - assuming you've removed the butt plug..

 

Like I said, false alarm. It was just my first time to get my new Acerbis tank low and I guess too much of the remaining gas was in wings and not at petcock.

I can run it 3N/4N/5N, it's just too rich at 5N since my float height must be a little different than yours.

Nope, didn't buy the wrong Kouba screw... And at least one of the people that reported the carb still working with mix screw seated all the way in didn't even have a Kouba screw. With that said, I'll check again for vacuum leaks. I've read it could even be an issue with damaged parts (like from PO overtightening screw at one point). The mix screw still functions... all the way in does get header pipe hot pretty fast. It's just not fully closing circuit apparently.

Yeah, my KLX300 exhaust didn't come with a buttplug.
It just has a CNC tip I ordered off ebay (non-restrictive).

I'll see how things run tomorrow at 3N. It may be perfect. Otherwise I'll just go back down to 4N.

 

OH OK, your using the 2206 needle.. The needle (352) in the 2206 kit is a very different animal.. Having just looked at mine in my KLX300, I can say that its' use is "outside the envelope" of my dyno tested setups with the 2152 kit (228 needle) kit.. No doubt that 5N would go horribly rich with that needle.. On the other hand, the 352 needle is designed to work with lid off - the 228 isn't..